Advanced Surface Ablation (ASA): PRK
Advanced Surface Ablation (ASA), formally known as PRK (photorefractive keratectomy), is a form of outpatient corneal surgery in which a surgeon removes the surface layer of cells on the cornea called the epithelium, and then reshapes the corneal bed with the laser in the same way as LASIK surgery. As in LASIK, ASA is a vision-correction procedure in which the excimer laser corrects myopia (nearsightedness), hyperopia (farsightedness), and astigmatism by permanently altering the shape of the cornea. ASA can reduce or eliminate the need for glasses or contact lenses. The difference is that ASA alters the cornea on its surface whereas in LASIK the corneal reshaping occurs within its body, or stroma. In ASA, no microkeratomes are used to create a corneal flap.
PRK with the VISX Laser was approved by the FDA in 1996 after the completion of trials that began in 1989. Studies have demonstrated that approximately 80% of eyes will see 20/20 one year after PRK. Ninety-five to 98% of eyes will see 20/40 or better, the level of vision required to drive without glasses in most states. PRK has evolved since its introduction in 1996 as current lasers are now faster and more precise, for smoother shaping and less scarring of the cornea. We use medications before, during, and after surgery that minimize pain and scarring. We use contact lenses during the healing period for more comfortable healing.
During PRK, the top layer of the cornea called the epithelium is removed to expose the cornea's mid-section, the stroma. Next, excimer laser is applied to reshape the stroma. Patients typically experience mild discomfort for several days after the procedure while the cornea’s surface layer regenerates. Special contact lenses and eye drops are used to help speed healing and minimize discomfort.
An Amoils brush is used to remove the epithelium
Laser energy is applied to reshape the exposed surface of the cornea
A pre-surgical examination can determine if your eye is healthy and suitable for ASA. This will include a complete physical and eye history, and a thorough examination of both eyes. In addition, computerized mapping of your cornea will be done to determine if it is smooth and properly shaped.
Before the surgery, please tell your doctor whether you take any medications or have any allergies. You should also arrange for transportation since you must not drive immediately after the surgery. You may resume driving only after receiving permission from our doctor.
After the surgery, you will be mildly sensitive to light and have the feeling that something is in your eye for the first few days. Sunglasses may make you more comfortable during this time.
Mild haze or cloudiness can be seen in the cornea following PRK but usually does not affect your vision. This haze tends to decrease over time and usually completely disappears over a 12 to 24 month period.
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